There are many types of devices comprising two or more subcompartments that are separated from each other by septa like, for example, monofilament screens, membranes, gels, filters, and fritted discs. Generally, these devices are assembled from a plurality of essentially parallel frames or spacers, separated from each other by the septa. Some of these devices comprise a repetitive assembly of functional units requiring only two compartments, such as a repetitive assembly of input and output subcompartments in a filter press.
The invention is of particular relevance to electrophoretic devices where three or more subcompartments are aligned, and wherein transport of solutes potentially occurs across all the compartments. For instance, in U.S. Pat. No. 4,362,612 issued to Bier, the adjoining compartments are functionally designed to electrophoretically adjust to different pH values, thereby separating dissolved proteins according to their isoelectric points. Similar multiple subcompartments devices are described in U.S. Pat. No. 4,971,670 issued to Faupel et al., U.S. Pat. No. 5,173,164 issued to Egen et al., U.S. Pat. No. 4,963,236 issued to Rodkey et al., and U.S. Pat. No. 5,087,338 issued to Perry et al.
All of the above patents disclose devices comprising a series of parallel spacers that are separated from each other by septa, which results in an essentially parallel array of subcompartments. Apart from the cited patents, numerous other such devices have been disclosed in patents and other publications. In all such devices, electrodes are provided at the ends of the assembly of subcompartments for the application of an electrical field.
Each subcompartment of these devices usually includes an input port and an output port for circulation of process fluid. The septa have a primary function of streamlining the flow of liquid without unduly hindering the intercompartmental transport of solutes due to electrical or diffusional forces. The septa in these devices may also have other functions, depending on the intended use of the apparatus. In some instruments, like the above-identified Bier and Egen et al. devices, the septa are simply monofilament screens of fine porosity, and the relatively open nature of the septa are used to minimize interaction with the electric process. In the Faupel et al. device, on the other hand, the septa constitute buffered membranes of polyacrylamide gels impregnated on fiber-glass filters. The intended purpose of the buffered septa is to control the transport of proteins across the membranes, limiting this transport to only proteins of certain polarity. In yet other devices (Perry et al., for instance) membranes of controlled porosity are used to separate solutes according to particle size. In the present application, the generic term septum is utilized to describe all of the above possibilities, as these are all compatible with the invention at hand. In addition to such inter-compartment septa, most instruments require physical containment of electrolytes used around the electrodes, for which the term membrane will be used.
The production, assembly and use of such devices is complicated and made difficult by the multitude of component spacers and septa, all of which have to be assembled in a parallel sequence and sealed against fluid leaks.